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L. e. NILSON'. PROPELLER.

APPLICATION FILED SEPT. 28, Hill.

Patented July 1, 1919.

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2 SHEETS-SHEET I.

L. G. NELSON.

PROPE'LLER.

APPLICATION FILED SEPLZB. 1911.

1308 5271 Patented July 1, 1919. 1 2 SHEETS-SHEET 2.

' Gr. NILSQN, F HOBOKER', NEW

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Specification of Letters Patent.

. Patented July 1,1919.

Application fled September as, 1917. Serial No. 193,627.

To all whom it may concern:

Be it known that I, LAns G. 'Ninson, a citizen of the United States, and resident of 'Hoboken, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in Propellers, of which the following is a specificatlonr This invention relates to propellers employed with aircraft, and my improvements are directed articularly to the construction of a propel er combining the features of strength and flexibility, together with such homogeneity of structure as will maintain the integrity thereof against the influences of vibration.

The standard aeronautic' ropeller of today is of wood, built 11 of different sections, glued together and a terward formed into shape.

ler ies not only in the diflicu ty of getting suitable material, but also the slow rocess of manufacturing; While the finishe product is not entirely satisfactory. Experience has shown that owin to the vibration caused b the engine as we 1 as the vibration due to t e motion through the air, the life of the ordinary wood propeller is comparatively short. As the power of the en'gme is produced by a series of ex losions the ropeller necessarily acts as a y-wheel. T ese impulses have a tendency to loosen the hub fastenings, and the continued vibration. also finally loosens the glue or cement which holds the different sections of wood together. Moisture and unfavorableatmosphenc conditions will also loosen the glue; and

' for military work the propeller is easily inj ured ordestroyed if hit by bullets or pieces of flying shrapnel. Man; proBfllers are also destroyed by unavoiab y 'tting objects when landing.

To overcome these difficulties I have invented a propeller having its hub or middle portion of metal and the win or blades partially flexible or resilient. e wings or blades are strong and rigid enough to perform the function of using up the power of the engine and at the same time are sufiiciently flexible to remain serviceable when pierced by a rifle bullet, and to prevent he objection to this type of propelbreaka if the propeller tips should-hit the groun when makin abadlanding.

Otherfeatures an advantages 0 my said invention will hereinafter appear.

In the drawings Figure 1 is a front elevation of my improved propeller.

Fig. 2 is a side elevation thereof..- Fig. 3 shows a group of crosssectional views respectively on the lines A-B, 0-D, EF, G-H, of Fig. 2.

Fig. 4 is an enlarged partial sectional view of the hub with details of the propeller framework or a supportin structure:

Fig. 5 is a detail viewo a portion ofthe propeller frame, showing a modification.

Figs. Sand 7 are respectively plan and side views of a stiffening element.

Fig. 8 is a partial view of a modified form of propeller, and Fi 9 and 10 are respectively front and si e views of a further modification.

In the production of my improved propeller the central or hub ortion 1 thereof is made of metal of'suita le form with an orifice to receive the propeller shaft, and is extended, in shell-like form, in the manner of sockets for a short distance alon the wings. The wingsor blades 2 are ma e of a slightly yielding elastic or flexible sub.-

' stance like vulcanized India rubber, braced or supported internally by the outwardly convergin arms 3 and 4, to which are fastened anc oring members '5. The arms 3 and 4 are securely fastened to the hub portion 1, fitting within the sockets thereon,

and should be made of spring-steel or similar material and so roportioned that they.

will bend slightly w en subjected to great -strain. They are ta red, the thickest portion bein at the hu and gradually becoming sma or toward the ends, so that the bending will also be adual. The arms 3 and 4 in a wing or bla e need not extend out to the extreme end thereof but can terminate at an desired point of its length. There shoul however, be embedded in the rubber a number of 'sprm stri s like that shown at 6 in Fi 6 and ese strips are vided with a small hook 7 to prevent t em from creeping and working out of the sun the points or tips of the propeller blades.

Whatever backbone is used for transmitting the torque must have stays, such as the cross bars, projections or ribs 5 to provide a suitable anchorage for the surrounding medium.

cially backed up properly,

. which seems most The detached spring strips 6, are to be embedded in the'rub'ber at the proper places, such as indicated, to add to the general stifi'ness. The rubber or composition comprising the mass material of which the propeller blades or wings are composed, may be reinforced in the manner well known, for example, in the art of tire construction, such as by the embedment therein of canvas, wovenfa'bric, cord, fiber, etc.

I have mentioned rubber as the material practical at the present time but other materials or compositions can be used,-for instance, bakelite, espereinforced and anchored to a hub of suflicient strength.

The form of my improved propeller shown in Figs. 1 and 2 is that of the conventional wooden propeller, but inasmuch as the central portion of any propeller does not add much to its efl'ectiveness a smaller hub and extended arms can just as well be used, as shown in Fig. 8. K

In amodification of my invention-shown in Figs. 9 and 10 the metal hub 8 may have radial extensions 9 of suitable form, preferably tapering toward the ends to be increasingly resilient in the outward direction,

which extensions may form respectively the cores for the propeller blades which may be composed of a suitable composition.

For instance, the blades as 10 may consist of canvas or the like impregnated with a suitable binding material, and squeezed into shape under pressure.

If rubber be used for the binder any desirable flexibility can be obtained, While if other material, like bakelite, be used a hard product results having a fine smooth surface and that is stronger than wood.

Obviously the blades may be made either detachable from the hub or Integral therewith.

Where my improved propeller is provided with .wings or blades made of non-resonant material it will be evident that the added advantage will beacquired of reducing the material, blades composed of molded rial, and means incorporated in said blades.

aeoaear noise created by the propeller whirling through the air.

Variations may be resorted-to within the spirit and scope of my said invention and parts thereof used without others.

in said sockets, and resilient stiifening means extending from said hub portions into said blades.

3. A composite propeller comprising a hub portion of rigid material, having radial sockets, blades of flexible material fitted in said sockets, resilient stiffening means extending from said hub portions into said blades, and anchorage means upon said stiffening means for said blades.

4. A composite propeller comprising a hub portion of rigid material, having radial sockets, blades of flexible material fitted in said sockets, stiffening means extending from said hub portions into said blades, and detachable spring strips embedded in said blades.

. 5. The combination, in a propeller, of a metal hub, a radial spring arm engaged therewith; .and a blade of flexible molded materal about said arm.

6. The combination, in a propeller, of a metal hub having a radial socket, a spring arm secured to said hub, and a blade of flexible molded material about said arm and en'- tered within said socket.

7. The combination, in a propeller, of a metal hub, a blade therefor of flexible material and a spring arm embedded Within said blade and secured to said hub, said arm characterized by diminishing in tension toward its outer end.

8. The combination, in a propeller, of a metal hub, a radial spring arm engaged therewith, said arm having projection, and a blade of flexible molded material about said arm and projections.

9; A propeller comprising a hub 0.. rigid mateto vary their lengthwise flexibility, whereby they may yield more readily toward their tips.

'10. A composite propeller comprising a metallic hub portion, radial extensions of said hub portion which are diminished outwardly ,to increase their resiliency, and blades 6f molded material formed about said extensions. a

11'. A composite propeller comprising a metallic hub portion, radial extensions of city county and State of New York, this said hub portion which are diminished out- 24th day of September A. D. 1917. wardly to increase their resiliency, and

blades of molded material formed about said LABS I NILSON' 5 extensions; said extensions having means of Witnesses:

engagement with said molded blades. F. W. BARKER,

Signed at borough of Manhattan in the A. B. BARKER. 

